Loudspeakers have been used for years for providing audio output to listeners. Electrical signals that are representative of various characteristics of sounds are transformed by the loudspeakers into vibrating movements of a diaphragm. These movements of the diaphragm create sound waves that can be heard by those nearby. Typically, the diaphragm of the loudspeaker is formed in the shape of a cone and audio waves are emanated from the cone in the general direction where the open end of the cone is pointed.
A loudspeaker typically employs a voice coil that is wrapped around a hollow cylinder or tube, made of such material as paper, aluminum or plastics, and positioned in the magnetic field of a permanent magnet. Also, the hollow cylinder or tube is connected to the diaphragm. When electrical current flows through the coil, a magnetic field is created around the hollow cylinder or tube that may either be attracted to or repelled by the magnetic field of the permanent magnet depending on the direction of the current flow. When the direction of current flow is reversed, the attractive or repulsion forces are also reversed. In this way, the hollow cylinder or tube can be moved back and forth, causing the diaphragm to move back and forth. This vibration creates the sounds that are produced by the loudspeaker.